From 74c7e58ea35cfec4bfd0b7aab0dbfe1b516ce3bd Mon Sep 17 00:00:00 2001
From: Jake Kaplan <jake@prefect.io>
Date: Thu, 6 Aug 2026 08:40:19 -0400
Subject: [PATCH] Expose configured discovery result
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---
 fastmcp_slim/fastmcp/client/client.py          |  5 +++++
 fastmcp_slim/fastmcp/server/providers/proxy.py |  2 +-
 tests/client/client/test_mode_negotiation.py   | 15 ++++++++++++++-
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/fastmcp_slim/fastmcp/client/client.py b/fastmcp_slim/fastmcp/client/client.py
index 55aff6408..ae1dde726 100644
--- a/fastmcp_slim/fastmcp/client/client.py
+++ b/fastmcp_slim/fastmcp/client/client.py
@@ -657,6 +657,11 @@ class Client(
 
         return self._session_state.session
 
+    @property
+    def prior_discover(self) -> mcp_types.DiscoverResult | None:
+        """The configured result to adopt when `mode` pins a modern version."""
+        return self._prior_discover
+
     @property
     def initialize_result(self) -> mcp_types.InitializeResult | None:
         """Get the result of the initialization request.
diff --git a/fastmcp_slim/fastmcp/server/providers/proxy.py b/fastmcp_slim/fastmcp/server/providers/proxy.py
index 5ad740c7b..d2f328051 100644
--- a/fastmcp_slim/fastmcp/server/providers/proxy.py
+++ b/fastmcp_slim/fastmcp/server/providers/proxy.py
@@ -1079,7 +1079,7 @@ class ProxyMetadataMiddleware(Middleware):
         if (
             not connected
             and client.mode in MODERN_PROTOCOL_VERSIONS
-            and client._prior_discover is None
+            and client.prior_discover is None
         ):
             client = client.new()
             client.mode = "auto"
diff --git a/tests/client/client/test_mode_negotiation.py b/tests/client/client/test_mode_negotiation.py
index 1d400a727..97c1fb3a8 100644
--- a/tests/client/client/test_mode_negotiation.py
+++ b/tests/client/client/test_mode_negotiation.py
@@ -22,7 +22,7 @@ from typing import Any
 import pytest
 from mcp import ClientSession
 from mcp.shared.exceptions import MCPError
-from mcp_types import METHOD_NOT_FOUND
+from mcp_types import METHOD_NOT_FOUND, DiscoverResult, ServerCapabilities
 from mcp_types.version import LATEST_HANDSHAKE_VERSION, LATEST_MODERN_VERSION
 from typing_extensions import Unpack
 
@@ -242,6 +242,19 @@ class TestNonConformantModernPeer:
 
 
 class TestPinnedMode:
+    def test_prior_discover_is_exposed(self, fastmcp_server):
+        prior = DiscoverResult(
+            supported_versions=[LATEST_MODERN_VERSION],
+            capabilities=ServerCapabilities(),
+        )
+        client = Client(
+            fastmcp_server,
+            mode=LATEST_MODERN_VERSION,
+            prior_discover=prior,
+        )
+
+        assert client.prior_discover is prior
+
     async def test_pinned_modern_adopts_without_probe(self, fastmcp_server):
         """Pinning the modern version adopts it directly; a synthesized
         DiscoverResult carries no identity, so server_info is absent."""